1. Field of the Invention
The present invention relates to a retaining structure of a disk holder. More specifically, the present invention relates to a retaining structure, which is used in a DVD/VCD/CD holder and is easily operated.
2. Description of the Related Art
Information recording medium such as DVD, VCD and CD need a holder to accommodate and protect them. A. DVD/VCD/CD holder known in the prior art comprises a plurality of L-shaped retainers that are formed in a circle at a central portion of a base of the holder. The circle formed by the L-shaped retainers has a diameter larger than a central opening of the DVD/VCD/CD. When the DVD/VCD/CD is to be placed on the retainers, the central opening of the DVD/VCD/CD deforms the retainers until the retainers pass through the central opening of the DVD/VCD/CD. Thereby, the retainers apply a clamping force to the DVD/VCD/CD. When the DVD/CD/CD is to be removed from the holder, the retainers are pressed down to release the clamping force applied on the DVD/VCD/CD.
U.S. Pat. No. 6,283,286, issued to the applicant of the present application, discloses another DVD/VCD/CD holder. This known holder structure includes a cover and a base 10a pivotally connected with the cover, as shown in FIG. 1. A retaining device 11a is formed at a central portion of the base 10a for securely clamping the DVD/VCD/CD. The retaining device 11a includes a disk centrally protruding from a ace of the base 10a, a plurality of L-shaped retainers 12a, a plurality of equally spaed slits 13a each having the L-shaped retainer 12a formed there between, a plurality of arcuate portions 15a each communicating with each slit 13a, a pressing portion 14a formed at the center of the disk and connected with each of the L-shaped retainers 12a by means of a bridge 16a, and a plurality of arcuate walls 18a formed on the disk between two adjacent slits 13a. The arcuate walls 18a and the L-shaped retainers 12a, which together fit a central opening of the DVD/VCD/CD, define a pressing portion 14a therein. A plurality of arcuate portions are formed along a rim of the pressing portion 14a in a manner that each arcuate portion 15 communicates with the slit 13a. The pressing portion 14a is connected with each of the L-shaped retainers 12a by means of a bridge 16a. A wedge 17a is formed on an external surface of each L-shaped retainer 12a for clamping a disk 20.
With reference to FIG. 3, a recess 19a is defined in a bottom of the base 10a to oppositely correspond to the pressing portion 14a to provide a space for removing the disk from the wedge 17a. 
With reference to FIG. 4, when the pressing portion 14a is pressed toward the recess 19a, the deformation of the pressing portion 14a forces all the L-shaped retainers 12a to tilt toward the pressing portion 14a and, therefore, to deform the circle formed by the arcuate walls 18a and the L-shaped retainers 12a. Thereby, the disk 20 is released from the wedge 17a. 
With the above conventional structure, when the disk is to be removed from the disk holder, a user has to press down the pressing portion to release the clamping force applied on the disk. If the pressing portion is not continuously pressed, the clamping force a the retainers immediately recovers. If the disk is not manually removed while the pressing portion is being pressed down, the disk is still retained in the holder. Therefore, the user has to use both hands at the same time to remove the disk from the holder. In addition to the above downside, the application of the retaining device is further limited to a thin disk holder. In this case, the pressing portion is not easily pressed down.
It is therefore a principal object of the invention to provide a retaining structure used in a disk holder, in which external edges of retainer of the retaining structure can keep a disk above the retainer after a central opening of the disk is released from the retaining structure. Therefore, the user only needs one hand to place or remove the disk by pressing down the pressing face.
In order to achieve the above and other objectives of the invention; a retaining structure formed on a base of a disk holder is provided. A retaining structure formed on a base of a disk holder, which comprises a holding portion formed on the base; a retainer including: a plurality of elastic pieces equally spaced on the holding portion, the elastic pieces each having a peripheral end being a free end; a pressing face positioned on a central portion thereof, and the pressing face connected to each of the elastic pieces through a connection part; a trench formed along an peripheral side of the pressing face; a plurality of wedges each formed on an external surface of each of the elastic pieces; and a plurality of arcuate walls each formed between two adjacent elastic pieces and separated from each of the elastic pieces by a slit communicated with the trench; and a recess Formed on the base of the disk holder and opposite to the retainer.
To provide a further understanding of the invention, the following detailed description illustrates embodiments and examples of the invention, this detailed description being provided only for illustration of the invention.